What is the most common attic insulation?

Author: Coralie Kautzer  |  Last update: Saturday, May 30, 2026

Fiberglass batt insulation is one of the most popular choices for attic insulation. Made from fine glass fibers, this type of insulation is available in pre-cut panels or batts, making it easy to install between standard joist and stud spacing.

What is the most effective attic insulation?

Cellulose is an eco-friendly and cost-effective insulation for attics. Fiberglass and mineral wool are also popular choices because they are good at keeping heat in or out and resist moisture and pests. Special equipment blows the loose-fill material into the attic spaces, ensuring it covers everything evenly.

Is R19 or R30 better for an attic?

Yes, you can use R19 insulation in an attic, but whether it's suitable depends on a few factors: Climate Zone: R19 insulation is typically appropriate for attics in moderate climates. In colder climates, higher R-values (like R30 or R38) may be recommended to effectively prevent heat loss.

What is the standard insulation for attics?

In most of California, the recommended R-value for attics is between R-30 and R-60. A professional insulation installer may assess your current insulation to determine its current R-value and what steps to take to bring it up to standards.

Should I remove old attic insulation before adding new?

Yes, it is generally advisable to remove old attic insulation before adding new insulation. Here are some reasons why: Moisture and Mold: Old insulation can retain moisture, which may lead to mold growth. Removing it allows you to inspect for any signs of water damage or mold that need to be addressed.

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Can I put too much insulation in my attic?

It is possible to over-insulate your house so much that it can't breathe. The whole point of home insulation is to tightly seal your home's interior. But if it becomes too tightly sealed with too many layers of insulation, moisture can get trapped inside those layers.

How often should attic insulation be replaced?

However, due to its construction with natural materials, eventually the product will lose effectiveness. Fiberglass insulation typically needs to be replaced 15-20 years into it's life, as it can easily become dirty, wet, moldy, and ineffective if there's a roof leak or water damage of any kind.

Is it OK to use R19 insulation in attics?

You will want to bring up your attic up to R-38:

If your attic has 5-6″ of existing insulation, you'll want to install an R-19 to achieve a total of R-38.

Is there a big difference between R13 and R15?

R15 insulation offers slightly better thermal insulative properties than R13. Some of its formats are a fraction of an inch thicker than R13, making it more effective at helping with energy efficiency. However, the difference is minimal.

What R-value is best for attic insulation?

The recommended R-value for attic insulation can vary depending on the climate zone in which you live. The U.S. Department of Energy recommends attic insulation levels of R-49 to R-60 for most homes in colder climates, and R-30 to R-49 for homes in warmer climates.

Can you double up R19 insulation?

If the existing attic insulation is an R-19, you may choose to add another layer of R-19. Two layers of R-19 at 6¼ ” thick will achieve a total R-value of 38. So adding an R-19 batt to an existing R-19 batt will give you a total insulation value of R-38.

Is R19 worth it over R13?

R13 insulation is generally more affordable, which makes it an attractive option for budget-conscious projects. However, R19 insulation offers better long-term advantages because of its higher R-value. Why? Because the R-Value translates to a greater energy savings over time.

What thickness is best for attic insulation?

The higher the R-Value, the better the thermal performance of the insulation. The recommended level for most attics is to insulate to R-38 or about 10 to 14 inches, depending on insulation type.

Which is better, attic insulation blown or rolled?

Blown fiberglass insulation scores an R-value of 3.2 to 3.8, making it slightly less likely than rolled fiberglass to prevent the flow of heat into and out of your house. That being said, though, blown fiberglass insulation isn't meant to cover huge areas like rolled fiberglass insulation.

What is the most expensive attic insulation?

The national average cost for common insulation types, such as fiberglass or blown in cellulose, is around $1.75 per square foot, while higher-end options like spray foam can reach up to $7 per square foot.

Is R19 or R30 better for attic?

While both types provide insulation, R30 is the better option for maximizing energy savings in areas where heat loss or gain is a major concern. For example, R19 may suffice for interior walls, but R30 is more appropriate for exterior-facing attics or floors.

Where should you not put insulation in the attic?

Also, when laying down additional insulation, work from the perimeter toward the attic opening. Never lay insulation over recessed light fixtures or soffit vents. Keep all insulation at least 3 inches away from recessed "can" lights, unless they are rated IC (Insulated Ceiling).

Where does R19 insulation go?

The most common application of R19 Insulation is in a vertical wall framed by 2×6 studs. As mentioned above this is a common code requirement in some parts of the United States.

Should attic insulation be faced or unfaced?

You can use faced or unfaced batting when installing between the roof rafters of finished attic spaces. When using paper or plastic batting insulation, that moisture barrier should face outward toward the attic space. Even if the attic space is unheated, it's typically warmer than the outside air in winter.

Does Lowes install insulation?

Lowe's is here to help with our blown-in and batt insulation installation service. There are two types of insulation material to choose from, and which one you choose is up to you. Cellulose insulation, made from recycled paper and treated to be fire-resistant, is the most common material used.

What is the labor cost to install insulation?

Most installers charge between $40 and $80 per hour to install insulation, so the more complex the project, the more it will cost. A few complexities that may increase the cost of labor include: Your installer needs to install insulation in hard-to-reach areas.

Can you put new attic insulation over old?

In many cases you can add new insulation on top of old insulation, unless the old insulation is wet, mouldy, or vermiculite. If the old insulation is dry but appears to have previously been wet, you should look for the cause and repair the problem.

What is the best insulation for the attic?

Fiberglass batt is considered to be the best insulation for attics. Compared to other insulation materials, it is the cheapest and easiest to install. Fiberglass batt is also incredibly energy efficient, as it helps to slow the spread of hot and cold air.

How do you tell if your attic is properly insulated?

Looking across your attic, if the insulation is level with or below the attic floor joists, you probably need to add more insulation. If you cannot see any of the floor joists because the insulation is well above them, you probably have enough, and adding more insulation may not be cost-effective.

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